Firing pin release mechanism



April 24, 1956 J. w. FARMER ET AL 2,742,860

FIRING PIN RELEASE MECHANISM Filed March 22, 1950 2 Sheets-Sheet l lellll-fllllllllllil INVENTOR.

JAMES W. FARMER BYMILLARD R.THOM$ON ATTORNEY April 24, 1956 J. w. FARMER ET AL 2,742,860

FIRING PIN RELEASE MECHANISM Filed March 22, 1950 2 Sheets-Sheet 2 k II I 54 54- I I 9 FIG. 5 4

- 54 26 44 44 I L 45 36 35 25 l 33 21 FIG.2 I I 'l2 0 I 9 T.

INVENT OR JAMES W. FARMER MILLARD R.THOM$ON ATTORNEY FIRING PIN RELEASE MECHANISM James W. Farmer and Millard R. Thomson, Lancaster, Pa., assignors to Hamilton Watch Company, Lancaster, Pa.

Application March 22, 1950, Serial No. 151,282

Claims. (Cl. 102--84) This invention relates to the triggering mechanism of a fuse for detonating bombs, artillery ammunition, demolition explosives or the like.

The object of the present invention is to provide a holding means for a firing pin and means for releasing said holding means after a predetermined interval of time, together with means for varying that interval within limits.

' A further object of the present invention is to provide a simple means for releasing a firing pin holding device after a predetermined interval of time, said means consisting in a vertically traveling nut with or without an annular traveling disc used in combination.

' A further object of the present invention is to provide a firing pin releasing means including a clockwork mechanism, an axially traveling nut operated by said clockwork mechanism, a rotatable disc also operated by said clockwork mechanism and used in combination with said axially traveling nut to maintain a releasing lever in firing pin holding position and to release said lever upon the expiration of a predetermined interval of time.

With the foregoing and other objects in view,'the invention resides in the novel arrangement and combination of parts and in the details of construction hereinafter described and claimed, it being understood that changes in the precise embodiment of the invention herein described may be made within the scope of what is claimed without departing from the spirit of the invention.

The invention is shown in the accompanying drawings r in which:

Figure 1 is a perspective view having portions cut away of the firing pin and lever holding means.

Figure 2 is a vertical cross section through the entire mechanism.

Figure 3 is a bottom view showing the plan of the clockwork movement.

Figure 4 is a top view showing the plan of the triggering mechanism.

Figure 5 is a sectional view of an alternate form of the triggering mechanism.

Figure 6 is a front elevation of the jig element.

Figure 7 is a top plan view of the jig element.

Referring particularly to Figure 2, a cylindrical body I portion 8 houses a mainspring barrel 9 having a mainspring 10 secured to a hollow shaft or arbor 11 which is journalled in bearings 12. The arbor 11 is fitted at its lower end with a plug 13 which carries a gear 14 at its lower end and is securely fastened to said arbor by a pin 15. Secured to the underside of the cylindrical body portion 8 is a clockwork mechanism 16 which serves to control the running down of the mainspring 10. This clockwork mechanism is secured to the body portion by screws 16' and is of the ordinary type and forms no part of this invention except in combination. A tubular shaft or arbor 11 houses but does not contact a cylindrical tube 17 which is formed on its upper end with an enlarged collar 18. The tube passes through and is press fit in a central hole in plate 37, the collar being seated on an 2,742,860 Patented Apr. 24, 1956 annular shoulder 18 formed in that plate hole. At its lower end the tube is inturned as shown at 19 and provided with a bushing 20.

Journalled in the bushing 20 is a firing pin 21 which is formed with an enlarged collar 22 at its upper end which is loosely seated in the tube 17. The lower end of the firing pin is tapered, as shown at 21, to provide an easy entrance into the bushing 20 when the firing pin is put in position. The plug 13 has a countersunk hole 13 to serve as clearance for the tapered end of the firing pin 21. Surmounting the collar 22 is a conical shaped firing head 23 which is carried entirely above the tube 17. Surrounding the rodlike body of the firing pin 21 is a coil spring 24 which bears against the bushing 20 at the lowermost end of the tube 17 and against the under portion of the collar 22 at the upper end of the firing pin. This spring in operation provides the force which projects the firing pin against the adjacent element of the fuse detonating train.

The arbor 11 is exteriorly threaded at 25 to receive a nut 26. The nut is slotted at 27 to engage a key pressed into a slot on the inside of ring '34. This key prevents rotation of the nut relative to ring 34. Secured to the upper end of the arbor 11 is a disc 28 which has an inner collar 29 and a pair of washers 30 secured thereto. Through the collar and a key 31 housed in keyway 31' the disc is secured to the arbor 11 and rotates therewith. This disc is provided with a peripheral notch 32 for reasons which will be hereafter explained.

Referring again to Figure 2, the body portion 8 is formed with an upstanding annular collar 33 to receive a ring 34 which has a downward reduced collar 35 fitting within the annular collar of the body portion and secured thereto by set screws 36. Plates 37 and 38 fit within an annular recess of this collar and are held in position by screws 39.

The plates 37 and 38 journal in a V-groove 40 a rod 40 which pivotally supports an L-shaped lever 41. This lever, at the end adjacent the pivot, engages the conical head 23 of the firing pin; the other end is provided with a finger 43 which contacts the outside wall of the nut 26. This lever is mounted for pivotal rotation about the rod 40 and is of such width as will permit it to enter the slot 32 of the disc 28.

In operation of the device rotation of arbor 11 is actuated by unwinding of mainspring 10; the rate of Irotation is controlled by-the clockwork movement 16, to which arbor 11 is connected by gear 14.

Rotation of arbor 11 causes a downward (toward the clockwork) axial displacement of nut 26 by reason of key 27, which prevents nut 26 from rotating in relation to ring 34. Thus, axial movement of the nut is propor= tional to lapse of time. The finger 43 of lever '41 rests upon the circumference of nut 26. When the nut has moved sufliciently downward that the finger 43 drops otf the rim 48 of the nut, the lever 41 falls upon and is held against further pivotal motion by engagement with the edge 49 of the disc 28. Further rotation of the arbor 11 and the disc 28, which revolves with it, brings the notch 32 opposite the arm 41 and permits additional pivotal motion of the lever 41 about the rod 40'. This pivoting of lever 41 releases the restraining force "exerted by end 42 of the lever 41 upon the cone-shaped head 23 of the firing pin and permits the spring 24 to expand. The expansion of spring 24 forces the firing pin into contact with the adjacent element of the fuze detonating train.

In the mechanism shown in Figure 5, the construction is primarily the same with an arbor 50 housing a firing pin 51 in a similar manner and provided with outside screw threads 52 for the axial travel of a nut 53-. The

pivoted levers 54 contact the top of the firing pin. The

' balanced restraint upon the firing pin and to prevent jar or shock from tripping the mechanism inadvertently. Operation of the firing pin is the same as in the previous form, the pivoting of levers about their pivot pins releasing the restraining force exerted upon the firing pin so that it is driven upward under the action of the coil spring to strike the adjacent element of the fuze detonating train.

The mechanism illustrated in Figure 5 shows duplicate restraining levers 54. This arrangement may be modified to include only a single lever or to include a multiplicity of levers, as required.

The power source of any of the abovedescribed mechanisms is a mainspring similar to a clock mainspring. The devices could be powered, without detriment to their function, by any other suitable means, such as centrifugal weights, torsion bars, etc.

' While this description covers a device designed for timing from 0 to 150 hours, the length of this timing range may be altered, by minor modifications to suit the circumstances.

Referring particularly to Figure 6, a jig is shown which is used for assembling the timing device. This jig consists of a bent metallic strip 58 having a screw 59 threaded into its uppermost portion. The jig is formed with two holes 60 for the reception of screws 61 to hold it to the top plate 38. The jig is screwed in place on the plate 38, the screw 59 contacting the conical head 23 and forcing it into cocked position as will be hereinafter described. This jig is an illustration of but one of many methods which could be used for assembly purposes.

The assembly of the device may be briefly described as follows: Mainspring is wound into barrel 9. Arbor 11 is set into bearing 12. Barrel 9 is then slipped into housing 8. Arbor 11 passesthrough the central hole in the closed end of the barrel, which lies adjacent to the closed end of housing 8. The mainspring is attached to arbor 11. The barrel cap 9 is set into position to cover the mainspring. Gear 14 is positioned on plug 13 and secured by three screws (not illustrated).

Clockwork movement 16 is moved into position at the open end of housing 8 and is secured by three screws 16 driven through the movement plates into'housing 8.

Nut 26 is screwed onto the threaded end of arbor 11. Disc 28 is screwed onto arbor 11 until upper surface of collar 29 is flush with the arbor end and keyways 31" are aligned; insert key 31, securing collar to arbor. Nut

26 is screwed toward disc 28 until they are almost in contact and key slot 27 and peripheral notch 32 are aligned.

Setting indicator ring 44, into which pin 46 has previously been pressed, is assembled to ring 34 and secured by screws 45. Firing pin spring housing 17 is pressed into hole provided in plate 37. Plate 37 is set into recess of ring 34. Rod 40' is assembled to lever 41 and the two are set into plate 37; the rod rests in V-groove 40 and the lever passes through a slot provided for it. Upper plate 38 is assembled and secured by screws 39. Firing pin spring 24 and firing pin 21 are inserted. Cooking jig 58 is assembled to plate 38 and secured by screws 60. By

' means of screw 59 hearing on firing pin head 23, spring 24 is compressed until it is somewhat overcooked. At this point, the lever 41 rocks freely on its supportin rod 40'.

The firing pin sub-assembly (which consists of the upper plate, the lower plate, the pawl, the spring, the tube 18 and the firing pin) is lowered into position with key 27 fitting into the keyway 27'. The two assemblies being abutted they are secured by turning set screws 36 sufficiently to engage the groove in the release housing.

The cocking jig 58 is now removed. The finger 43 of the pawl now rests on the shoulder 62 of the nut 26, which nut'is linked to the release housing by the key 27. A straight setting pin, not shown, is inserted through the setting pin hole 63 (Figure 4) of the upper plate 38 and the entire release housing rotated until a light pressure pushes the pin into slot 32 of the timing disc 28. This positively locates the timing disc with relation to the pawl 41, the angular distance between the pawl and the hole 63 being predetermined. The setting pin is held in this position while the release housing is rotated clockwise, driving the nut 26 down the arbor until the finger 43 drops ofi of the shoulder 62, which point is easily ascertained by the click of the finger against the edge of the nut. During the above-described operation, disc 28 is rotated in respect to arbor 11 by virtue of the fact that the force applied to the disc through the setting pin is suflicient to overcome the friction between hub 29, disc 28 and washers 30; note that when the device is functioning as a timing unit this friction is adequate to ensure that disc 28 rotates with arbor 11 without any difference of rotation due to slippage in the friction-disc hub assembly. Set screws 36 are at once turned tight to lock the two housings together. The device is so designed that at this point -.the long-end point of the hold-down lever will rest upon the cylindrical surface of the nut for approximately 144 hours running time.

The setting pin is now removed. Setting pin hole 63 is so positioned that setting pin action has placed notch 32 96 or 4 hours running time ahead of the position of hold-down lever 41. Maintaining the positions of the housing 8 in relation to ring 34, the setting indicator ring 44 is rotated on ring 34 until its ll-hour graduation is opposite the index mark on housing 8. Set screws 45 are then secured. Next, thesetting revolution counter wheel 47 is set at its l35-hour indication and secured against free rotation.

Finally, the ring 34 is rotated through 96 (12-hour, 13-hour, 14-hour markings) until the zero indication of setting indicator ring 44 coincides with 15 0-hour indication of the setting revolution counter wheel 47. The device is now set for hours run.

What is claimed is:

1. A firing pin release mechanism for mechanical time fuzes, comprising a clockwork mechanism, an exteriorly threaded hollow arbor connected to and rotated by the mainspring of said clockwork mechanism, a nut threaded on said arbor and adapted for non-rotative longitudinal travel of said arbor, a tube housed within said hollow arbor, a coil spring within said tube, a firing pin adapted to be housed within said tube and to compress said spring, a pivoted lever engaging said firing pin when in spring compressing position, the free end of said lever engaging the outer side of said longitudinal traveling nut, whereby disengagement of said lever with said nut due to the longitudinal travel of said nut will release said firing pin. 2. A firing pin release mechanism for mechanical time fuzes, comprising a cylindrical casing, a source of power housed within said casing, a tubular shaft mounted for rotation within said casing and adapted to be rotated by said source of power, a firing pin housed within said tubular shaft, a compression spring substantially surrounding said firing pin, a cylindrical collar adapted to be attached to and form part of said cylindrical casing, a lever pivotally mounted in said collar, one end of said lever engaging said firing pin and holding it in spring compressing position, means actuated by said rotating tubular shaft engaging the free end of said lever, whereby rotation'of said tubular shaft will release said lever and consequently said firing pin.

3. A firing pin release'mechanism for mechanical time fuzes, comprising a cylindrical casing formed with an upstanding-annular collar, a mainspring housed within said casing, a clockwork mechanism attached to said mainspring to control the rotation thereof, a hollow cylindrical arbor attached to said mainspring and rotated thereby, said arbor extending above said cylindrical casing, the part of said arbor extending above said cylindrical casing being exteriorly threaded, a nut mounted for nonrotative longitudinal movement on said upper portion of said arbor, a disc formed with a peripheral slot mounted for rotative movement at the extreme upper end of said arbor, a tube carried within said hollow cylindrical arbor, a firing pin formed with a long cylindrical body portion and a firing head, a coil spring carried around said firing pin, said coil spring and said firing pin being housed within said tube, the coil spring bearing against the bottom of said tube and the head of the firing pin, a cylindrical ring having an annular downwardly extending shoulder fitting within the upstanding collar of said cylindrical casing, said cylindrical ring being annularly adjustable with respect to said cylindrical casing, a pair of plates attached to said cylindrical ring, a lever pivotally mounted between said plates and bearing at one end on the head of said firing pin, the other end of said lever being formed with a finger adapted to bear against the longitudinal traveling nut and said rotating disc in turn, whereby rotative movement of the arbor will move said nut away from said finger and subsequent rotative movement of said disc will bring the peripheral slot into alignment with said lever permitting said lever to pivot and release said firing pin.

4. A firing pin release mechanism for mechanical time fuzes, comprising a cylindrical casing formed with an upstanding annular collar, a mainspring housed within said casing, 21 clockwork mechanism attached to said mainspring to control the rotation thereof, a hollow cylindrical arbor attached to said mainspring and rotated thereby, said arbor extending above said cylindrical casing, the part of said arbor extending above said cylindrical casing being exteriorly threaded, a nut mounted for nonrotative longitudinal movement on said upper portion of said arbor, a disc formed with a peripheral slot mounted for rotative movement at the extreme upper end of said arbor, a tube carried within said hollow cylindrical arbor, a firing pin formed with a long cylindrical body portion and a firing head, a coil spring carried around said firing pin, said coil spring and said firing pin being housed within said tube, the coil spring bearing against the bottom of said tube and the head of the firing pin, a cylindrical ring having an annular downwardly extending shoulder fitting within the upstanding collar of said cylindrical casing, said cylindrical ring being annularly adjustable with respect to said cylindrical casing, means for measuring the angular distance from the contacting position of said lever and said arbor rotating disc to said peripheral slot, means for locking said cylindrical casing and said cylindrical ring after said annular adjustment, a pair of plates attached to said cylindrical ring, a lever pivotally mountedbetween said plates and bearing at one end on the head of said firing pin, the other end of said lever being formed with a finger adapted to bear against the longitudinal traveling nut and said rotating disc in turn, whereby rotative movement of the arbor will move said nut away from said finger and subsequent rotative movement of said disc will bring the peripheral slot into alignment with said lever permitting said lever to pivot and release said firing pin.

5. A firing pin release mechanism for mechanical time fuzes, comprising a clockwork mechanism, a cylindrical casing housing said clockwork mechanism, a hollow tubular arbor connected to and rotated by said clockwork mechanism, the upper part of said arbor extending above said casing and being exteriorly threaded, a nut mounted for non-rotative longitudinal movement on said exteriorly threaded arbor, a firing pin assembly including a compressed spring mounted within said tubular arbor, a cylindrical ring carried above and secured to said cylindrical casing, a pair of levers pivotally mounted in said cylindrical ring and engaging said firing pin and said nut, whereby rotative movement of said arbor will move said nut relative to said levers and release said firing pin.

References Cited in the file of this patent UNITED STATES PATENTS 1,288,797 Asbury Dec. 24, 1918 1,362,519 Wilck Dec. 14, 1920 1,558,260 Glass Oct. 20, 1925 2,514,499 Kharasch July 11, 1950 FOREIGN PATENTS 72,889 Sweden Oct. 6, 1931 

